Proposed Concept Two Ns slot, Np pole winding are formed each - PowerPoint PPT Presentation

Proposed Concept • Two Ns slot, Np pole winding are formed each having coil pitch = 2 X slot pitch • These two windings (W1, W2) are mechanically phase shifted by an angle 𝜄 𝑡ℎ • To eliminate certain harmonic, 𝜉 this shifting should be selected as 𝜄 𝑡ℎ = 3𝜌/𝜉 • Having wye-delta connection within two coils for each of these windings (W1 and W2) make the current angle electrically 30 degree shifted in time and their positions results 30 degree electrical shift in space. As a result, the resultant MMF for the first sub-harmonics ( 𝜉 = 1) becomes zero. It also enhances the torque-producing component. • The resultant stator configuration has twice the number of slot compare to their concentrated wound counterparts which also helps in minimizing cogging torque and this also helps in minimizing torque ripple. 1

Analytical Model W1 MMF W2 MMF 𝜄 1 𝜄 1 2 Π /6 Π /6 Wye Delta Wye Delta 1 = 𝑁𝐽 sin 𝑙𝜌 12 sin 𝑙 − 1 𝜌 sin 𝑙𝜄 − 𝜕𝑢 − 𝑙 − 1 𝜌 𝑁𝑁𝐺 12 12 𝑁𝑁𝐺 2 = 𝑁𝐽 sin 𝑙𝜌 12 sin 𝑙 − 1 𝜌 sin 𝑙 𝜄 − 𝜄 1 − 𝜕𝑢 − 𝑙 − 1 𝜌 12 12 𝑁𝑁𝐺 𝑈 = 2𝑁𝐽 sin 𝑙𝜌 12 sin 𝑙 − 1 𝜌 sin 𝑙𝜄 − 𝜕𝑢 − 𝑙 − 1 𝜌 − 𝑙𝜄 1 cos( 𝑙𝜄 1 2 ) 12 12 2 𝑙𝜄 1 2 = 90 𝑝𝑠 270 ⇒ 𝜄 1 = 77.15 𝑒𝑓𝑕𝑠𝑓𝑓 = 5𝜌 To eliminate 7 th Harmonics 24 + 2.14 𝑙𝜄 1 To eliminate 5 th Harmonics 2 = 270 ⇒ 𝜄 1 = 108 =7*pi/24+3 2

Winding Configuration Proposed winding Layout W2 W1 θ sh (W1 and W2) W2 W1 θ sh (W1 and W2) Coil configuration 3

Results Conventional 10P/12S 10P/12S with wye-delta Proposed 10P/24S Air-gap MMF Harmonics Air-gap MMF Harmonics 1.25 Percentage Relative to the 1.2 Harmonics (% relative to 1 1 main component) main component 0.8 0.75 0.6 0.4 0.5 0.2 0.25 0 1 3 5 7 11 13 17 19 0 Harmonics number 1 5 9 13 17 (a) (b) (c) • From conventional 10P/12S (Fig. a), the first sub-harmonic is eliminated with wye- delta connection (Fig. b). The torque producing component is also enhanced by 3.5%. From Fig. b, the unwanted 7 th harmonic is eliminated by proposed coil shifting • concept. This also reduces the higher order harmonics like 17 th , 31 st , 41 st etc. • Overall, compare to the conventional 10P/12S winding (Fig. a), the proposed concept (Fig. c) reduces THD by 61.22% and enhances the fundamental by 1.5%. 4